Cryosurgical Instrument and Its Accessory System

ABSTRACT

The invention proposes a cryosurgical instrument and its accessory system operating on the base of a refrigerant evaporation. The invention comprises combination of some technical solutions. Flow in a central lumen of the cryosurgical instrument has oscillating character; the refrigerant is provided on the internal surface of the distal cryotip in the form of separated portions. 2. The internal surface of the distal cryotip of the cryosurgical instrument is covered by a porous coating, which soaks completely one portion of the refrigerant. 3. Vapors obtained as a result of the refrigerant boiling on the porous coating of the cryotip are removed through the central lumen into the atmosphere. Combination of these technical solutions allows to construct a safely cryosurgical instrument with high freezing power and small outer diameter. The proposed cryosurgical instrument may be designed as a flexible cryocatheter or as a rigid cryoprobe.

CROSS REFERENCE APPLICATION

This patent application is a continuation application of non-provisionalapplication Ser. No. 11/531,058 filed 12 Sep. 2006, which is acontinuation of non-provisional application Ser. No. 10/637,904 filed 11Aug. 2003, now U.S. Pat. No. 7,137,978, which claims the benefit of theearlier filed Israeli Patent Application Ser. No. 151486 filed 26 Aug.2002, all of which applications are hereby incorporated herein byreference in their entirety.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND OF THE INVENTION

There is significant number of patents, especially, the USA patents,which describe different constructions of cryosurgical probes andcatheters. An aim of these patents is to solve some main problems, whichare common to cryosurgical probes and catheters.

The problems include construction of relatively cheap and simple probesor catheters with high reliability and sufficiently effective thermalinsulation of their lateral non-operating walls. Besides, cryosurgicalcatheters must have high flexibility, especially, when they are used forcardiac interventions. At the same time the closed distal end (cryotip)of such probe or catheter must provide in many cases high specificfreezing capacity at sufficiently low-temperatures.

Analysis of USA patents related to this field shows, that constructionsof the proposed probes and catheters intended for cryosurgery do notconform the above-mentioned requirements.

For example, U.S. Pat. No. 3,971,383 proposes a cryogenic surgicalinstrument with a coaxial assembly of the flexible lumens; the inner onebeing connected to a supply of cryogenic liquid, and the space betweenthe outer wall of the inner lumen and the next lumen forming a returnline for evaporated cryogenic liquid which is vented to the atmosphere;and the space between the outermost one of the coaxial lumens and theintermediate lumen containing a gas, such as normal butane, serving forthermal insulation of the inner and intermediate lumens.

U.S. Pat. No. 5,716,353 describes a probe for cryosurgery which consistsof three lumens: an inner lumen for supply a cryogenic refrigerant to acryotip positioned on the distal end of an outer jacket lumen, and anintermediate lumen situated concentrically around the inner lumen. Thechannel between the inner and intermediate lumens serves as a ventingpath for venting cryogenic refrigerant from the freezing zone. Thisconstruction is simple, but it does not provide sufficient thermalinsulation as required in construction of a cryogenic catheter.Consequently, it may cause over-heating of the venting cryogenicrefrigerant, as well as over-cooling of tissues adjacent theintermediate section of the catheter.

U.S. Pat. No. 5,573,532 describes design of a cryosurgical instrument,which comprises lumens of cryogenic fluid supply and return of cryogenicfluid vapors; these lumens are situated concentrically and the returnlumen is sealed with a cryotip. The patent proposes to do vacuuminsulation of the return lumen. Such construction is very expensive andhas low reliability. Besides, this vacuum insulation limits flexibilityof the probe, especially, when it has significant length and is used asa catheter.

U.S. Pat. No. 5,674,218 describes a cryosurgical instrument, a systemand method of cryosurgery. According to this patent a cryogenic liquid(preferably, liquid nitrogen) is preliminary sub-cooled below its normalboiling point and in such condition it is supplied into the openproximal end of the internal supply line. The outer lumen of thecryosurgical instrument is provided with active vacuum insulation.

Obviously, this construction cannot ensure high flexibility and cannotbe used as the base for construction of a catheter for cryosurgery.

U.S. Pat. No. 5,254,116 describes a cryocatheter with a set of ventholes in the lateral wall of a central feeding lumen; besides,sub-cooled liquid nitrogen is delivered into the central feeding lumenas a cryogenic liquid. This construction does not ensure proper thermalinsulation of the cryocatheter.

BRIEF SUMMARY OF THE INVENTION

This invention proposes novel designs of a cryosurgical instrument andits accessory system. The cryosurgical instrument is constructed fromtwo major sub-units: a distal cryotip, which serves for immediatecontact with a target tissue to be treated; freezing action of thiscryotip is obtained by evaporation of a cryogenic liquid on its internalsurface covered with a porous coating with open porosity; an elongatedtubular sub-unit serving for delivery of portions of the cryogenicliquid on the distal cryotip with following removal of vapors generatedin the process of boiling this cryogenic liquid in the porous coating ofthe distal cryotip.

The elongated tubular sub-unit in turn comprises following details: anexternal shaft and a central feeding-venting lumen, which serves forimmediate supply of portions of the cryogenic liquid to the porouscoating of the distal cryotip and, at the same time, for removal of thevapors, generated in the process of boiling the cryogenic liquid on theinternal surface of the distal cryotip, into the atmosphere or into avacuum pump.

In addition, there is a coaxial tubular piece positioned in the gapbetween the distal sections of the central feeding-venting lumen and theexternal shaft; the distal end of this coaxial tubular piece is sealedwith the external shaft or with the cryotip itself and the proximalend—with the central feeding-venting lumen. It forms a buffer spacebetween: the internal surface of the cryotip, the centralfeeding-venting lumen and the coaxial tubular piece, this buffer spacefacilitates flow of the portion the cryogenic liquid in the centralfeeding-venting lumen toward the cryotip.

The proximal section of the external shaft and proximal end of thecentral feeding-venting lumen are provided with inlet-outletconnections.

In another version there is a coaxial intermediate lumen, which issituated between the central feeding-venting lumen and the externalshaft. This coaxial intermediate lumen substitutes the aforementionedcoaxial tubular piece. The distal end of this coaxial intermediate lumenis sealed with the external shaft or with the cryotip itself; theproximal end—with the central feeding-venting lumen, and the proximalend of the external shaft—with the proximal section of the coaxialintermediate lumen. The proximal section of the coaxial intermediatelumen is provided in this case with an outlet connection.

When the proposed construction is used as a cryocatheter, the externalshaft is made preferably from polymer material, it allows to achieve itshigh flexibility.

The cryotip of the cryocatheter should be made from material with highthermal conductivity (for example, copper, silver, diamond, BeO). As ithas been noted, the internal surface of cryotip is covered with a porouscoating with open porosity (for example, this porous coating is obtainedby sintering copper powder). This provides high magnitudes of the heattransfer coefficients in the process of boiling the cryogenic liquid.Besides, this porous coating can completely soak one portion of thecryogenic liquid provided by an accessory system during firstquarter-period of its operation as it will be described thereafter.

The proposed cryocatheter can be used for inhibiting restenosis of ablood vessel. In this case the cryotip is constructed in the form of atubular detail, the distal end of the tubular detail is sealed with aplug from polymer with low thermal conductivity and its tubular sectionis fabricated from a thin polymer film with high elasticity, theinternal surface of the tubular section is coated with a porous polymerlayer with open porosity, this porous polymer layer has also highelasticity.

Construction of the accessory systems for these two designs of thecryocatheter (or cryoprobe) will be described thereafter as well.

A first version of the accessory system, which ensures desiredfunctioning of the proposed cryosurgical instrument, comprises: athermo-insulated tank filled with the cryogenic liquid, thethermo-insulated tank is provided with a relief valve which givespossibility to preset the desired pressure in this thermo-insulatedtank; a feed pipe which is situated vertically and the lower end of thisfeed pipe is positioned near the bottom of the thermo-insulated tank. Anoutlet connection of the feed pipe is joined by a flexiblethermo-insulated duct with an inlet connection of a multi-way valve.This multi-way valve is provided with an additional inlet connectionwhich is communicated with a bottle with pressurized gas (for example,nitrogen), an outlet connection which is communicated with atmosphere(or a vacuum pump), and with an inlet-outlet connection which iscommunicated with an inlet-outlet connection of the centralfeeding-venting lumen of the cryosurgical instrument itself.

In addition, there are four shut-off valves, the first shut-off valve isinstalled on a main duct which communicates the multi-way valve with theinlet-outlet connection of the central feeding-venting lumen of thecryosurgical instrument, the second one—on a duct which communicates theoutlet connection of the thermo-insulated tank with the multi-way valve,the third one—on the duct which communicates the bottle with pressurizedgas and the multi-way valve, and the fourth—on the thermo-insulated tankitself; this shut-off valve serves for filling the thermo-insulted tankwith the cryogenic liquid. The fourth shut-off valve is open duringfilling the thermo-insulated tank with the cryogenic liquid; the secondone serves for cutting off supply of the cryogenic liquid to themulti-way valve, the third one—for cutting off supply of pressurized gasto the multi-way valve and the first one—for putting in action thecryosurgical instrument.

An electromechanical (or pneumatic) drive ensures periodical with presetfrequency changeover of the multi-way valve in such a way, that it iscommunicating alternatively with: the thermo-insulated tank, the bottlewith pressurized gas, and the atmosphere (or the vacuum pump).

A control unit keeps watch on frequency of changeover of the multi-wayvalve and, in the case of significant deviation from the presetfrequency of changeover or its stoppage, this control unit activates theaforementioned second and third shut-off valves. In addition, it ispossible to install pressure and temperature gauges on the main duct ofthe accessory system. Data provided from these gauges-are processed inthe control unit. In the case of significant deviations of the measuredparameters from the preset values, the control unit cuts off theshut-off valves installed on the main, first and second ducts.

Significant fraction of the cryogenic liquid, which remains in theporous coating of the cryotip and in the aforementioned buffer space inthe period between communication of the central feeding-venting lumenwith the inlet connection of the vacuum pump (or with the atmosphere)and communication this central feeding-venting lumen with the feedingpipe of the thermo-insulated tank, generates reasonably high pressure inthe central feeding-venting lumen; this pressure prevents introducingthe following portion of the cryogenic liquid into the centralfeeding-venting lumen.

In the aforementioned case of application of the coaxial intermediatelumen with an outlet connection instead of the coaxial tubular piece,there is an auxiliary shut-off valve installed on a duct communicatingthe outlet connection of the coaxial intermediate lumen with theatmosphere (or with the vacuum pump); this shut-off valve is joined withthe multi-way valve mechanically or electro-mechanically in such a way,that it will be open only at a quarter-period, when the multi-way valveis communicating the main duct with the bottle with pressurized gas.

In addition, the outlet connection of the intermediate lumen can serveas an inlet-outlet connection. In this case a gas from a special bottleis provided into the gap between the coaxial intermediate and thecentral feeding-venting lumens; introduction of this gas is performedwhen the multi-way valve communicates the central feeding-venting lumenwith the atmosphere (or the vacuum pump).

The ducts between the thermo-insulated tank and the multi-way valve, andbetween this multi-way valve and the inlet-outlet connection of thecentral feeding-venting lumen can be provided with outer thermalinsulation, for example, with vacuum insulation.

There are several cryogens that can be applied as the cryogenic liquid:liquid nitrogen, liquid argon, liquid R14 and others.

Besides, it is possible to apply two tanks with different liquids: thefirst one—a cryogenic liquid with low temperature of boiling (forexample, liquid nitrogen), which serves for cryogenic treatment oftarget tissue, and the second one—with relatively high temperature ofboiling (for example, R12B1 that boils at temperature −3.8.degree. C. atatmospheric pressure), this second liquid serves for ice-mapping.

The second liquid with normal boiling temperature higher than 0.degree.C. (for example, R11, which has normal boiling temperature 23.65.degree.C.) can be used for fast thawing a tissue, which has been previouslyfrozen by the cryogenic liquid.

Application of two liquids with high difference in their boilingtemperatures requires performance of blowing the central feeding-ventinglumen, the buffer space and several ducts in the period between theprocedures of ice-mapping (or thawing) and following cryogenictreatment.

The accessory system comprises in this case two accessory sub-systems,each of these accessory sub-systems is constructed much as the accessorysystem, which has been described above. The accessory sub-systems have acommon control unit and a common main duct which splits off into twoducts communicated correspondingly with first and second multi-wayvalves; a thermo-insulated tank of the first accessory sub-systemcontains a cryogenic liquid which serves to freeze the target tissue,and a tank of the second accessory subunit contains a liquid withrelatively high temperature of boiling (for example, R12B1 or R11), thisliquid serves for preliminary ice-mapping (as with R12B1); or for fastthawing this target tissue (as with R11).

The accessory system comprises in addition an auxiliary accessorysub-system, which serves for blowing the cryosurgical instrument and theducts communicating the first and second accessory sub-systems with thiscryosurgical instrument. The auxiliary accessory sub-system consists ofan auxiliary bottle with pressurized gas and an auxiliary three-wayvalve, which is installed on a duct communicating the auxiliary bottlewith the main duct. The auxiliary three-way valve is regulated by thecommon control unit, and it has two outlet connections, the first outletconnection of this auxiliary three-way valve is communicated with themain duct and the second one—with the atmosphere or a vacuum pump.

Blowing process is performed by cutting out the shut-off valvesinstalled on the ducts communicating the tanks with their associatedmulti-way valves and then pressurized gas from the bottle performsblowing the main duct and the ducts generated by its splitting off, thecentral feeding-venting lumen and the buffer space by charging andpurging technique.

As stated above, the gap between the central feeding-venting lumen (orthe coaxial tubular piece) and the external shaft serves for thermalinsulating the external shaft, especially, its distal section in orderto prevent possibility of negative temperature on its outer surface.

It is possible to achieve higher degree of thermal insulation of theexternal shaft of the cryosurgical instrument by preliminary filling thegap between the external shaft and the coaxial tubular piece with a gas,which has very low thermal conductivity, and, on the other hand,condensation temperature of this gas is lower than the boilingtemperature of the cryogenic liquid. In order to perform this filling,the proximal section of the external shaft is provided with aninlet-outlet connection; the accessory system comprises a bottle withthe aforementioned gas with low thermal conductivity, and a duct, whichcommunicates this bottle with the inlet-outlet connection of theexternal shaft, is provided with a three-way valve, which iscommunicated as well with the atmosphere or with a vacuum pump. Itallows to perform filling the gap between the external shaft and thecoaxial tubular piece by charging and purging technique.

In order to achieve better characteristics of thermal insulation of thedistal section of the external shaft (to prevent negative temperature ofits outer surface) it is possible to apply a heat pipe principle.

In this case, the heat pipe principle is realized in the followingmanner: the outer surfaces of the coaxial tubular piece and a section ofthe central feeding-venting lumen mating this coaxial tubular piece arecovered with a porous coating with open porosity, this coating isfunctioning as a wick. The gap between the external shaft and thecoaxial tubular piece, and its extension to the gap between the centralfeeding-venting lumen and the external shaft is filled with such a gasthat the temperature of its condensation somewhat higher than theboiling temperature of the cryogenic liquid, but the solidificationtemperature of this gas should be somewhat lower than the boilingtemperature of the cryogenic liquid. This gas can be provided into thesegaps via the inlet-outlet connection installed on the proximal sectionof the external shaft.

Charging and purging technique can perform it. Such technical solutionpermits to heat the distal section of the external shaft at the expenseof the heat provided to the intermediate and proximal sections of theexternal shaft from the surroundings.

It should be noted that the multi-way valve can be substituted for a setof shut-off valves installed on the communicating ducts; coordinatedoperation of this set of the shut-off valves simulates operation of theaforementioned multi-way valve.

The cryosurgical instrument constructed according to this invention canbe provided with a thermocouple, which is positioned in the cryotip andmeasures temperature in this cryotip in the process of a cryosurgicaloperation.

Besides, if the cryosurgical instrument is designed as a cryocatheter,this cryocatheter should be provided with a steering mechanism allowingbending its distal section.

The cryotip of the cryocatheter (or cryoprobe) may be provided with anelectrode for preliminary detection of electrical signal activity ofdifferent places of the organ to be operated.

Operation of the cryosurgical instrument and its accessory system isperformed in a following manner.

A portion of the cryogenic liquid is introduced via the feed pipe of thethermo-insulated tank into the duct communicating the multi-way valvewith the inlet-outlet connection installed on the proximal end of thecentral feeding-venting lumen (in the following, this duct will becalled—the main duct), it occurs at a quarter-period, when the multi-wayvalve is in such position, that the cryogenic liquid may flow from thefeed pipe into the main duct (it is a first quarter-period).

Thereafter the multi-way valve ceases flow of the cryogenic liquid fromthe thermo-insulated tank into the main duct and at the following secondquarter-period the multi-way valve communicates the bottle with thepressurized gas with the main duct, which provides high velocity to theportion of the cryogenic liquid and this portion passes briefly the mainduct and the central feeding-venting lumen, and reaches the porouscoating of the cryotip.

Then supply of the pressurized gas is ceased and the multi-way valvecuts off the proximal end of the main duct. The cryogenic liquid isboiling in the porous coating of the cryotip with elevation of pressureof the cryogenic liquid vapor in the central feeding-venting lumen andthe main duct (it is a third quarter-period).

At the fourth quarter-period the multi-way valve turns on the ductcommunicating the main duct with the atmosphere or with the vacuum pump.Boiling the cryogenic liquid in the porous coating of the cryotip can becontinued in this quarter-period. It is well to bear in mind that allaforementioned quarter-periods may have different duration.

In the case when the cryosurgical instrument is designed as acryocatheter, which is intended to treat a blood vessel in order toprevent restenosis and its cryotip is constructed from elastic polymer,it is very important to keep relatively low excessive pressure in theinternal chamber of the distal section of this cryocatheter with smalldeviation from its average value. In order to provide these conditions,the cryocatheter is constructed with the intermediate lumen as it hasbeen described above. The outlet connection of the intermediate lumen isprovided with a T-shaped manifold, which comprises a crossbar and a mainsection intersecting perpendicularly with the crossbar. A pressure gaugeis installed on one end of the crossbar and an adjusting valve isinstalled on the other end, this adjusting valve is connected with theatmosphere or with the vacuum pump. Signals from the pressure gauge aresent to a pressure control unit, which provides in turn desiredoperation of the adjusting valve. It should be noted that the pressurecontrol unit could be interconnected with the aforementioned controlunit, in doing so operations of these control units are correlated.

It is the primary object of the present invention to provide a flexiblecatheter with high flexibility, high specific freezing power andsufficiently small diameter for cryosurgical procedures in differentareas of medicine.

It is another object of the invention to provide a rigid probe with highspecific freezing power and sufficiently small diameter for cryosurgicalprocedures in different areas of medicine.

It is an additional object of the invention to design a cryosurgicalinstrument and its accessory system for cryosurgical procedures, whichhave high degree of safety and reliability. It should be noted that theproposed design of the cryosurgical instrument ensures positivetemperatures at the distal section of its external shaft, especially, inthe immediate vicinity of the cryotip.

It is another object of this invention to develop a novel method ofthermal insulation of the distal section of the external shaft of thecryosurgical instrument, this method is based on the principle of a heatpipe.

It is another object of this invention to design a cryocatheter that isused for inhibiting restenosis of a blood vessel.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Other objectives of this invention will be apparent from the followingdetail description taken in conjunction with the accompanying drawings,in which:

FIG. 1 is a general view of a cryosurgical instrument of the presentinvention and a block diagram of its accessory system.

FIG. 2 is a general view of a cryosurgical instrument of the presentinvention and a block diagram of its accessory system, when there is acoaxial intermediate lumen situated between a central feeding-ventinglumen and an external shaft with oscillating flow in the channel betweenthe central feeding-venting and coaxial intermediate lumens.

FIG. 3 is a general view of a cryosurgical instrument of the presentinvention and a block diagram of its accessory system, when twodifferent liquids are used for preliminary ice-mapping and followingcryogenic treatment.

Besides, this drawing demonstrates a general view of a cryosurgicalinstrument and a block diagram of its accessory system in the case ofapplication of two different liquids for freezing and fast thawing atarget tissue.

FIG. 4 is an axial cross-section of the cryosurgical instrument withapplication of active thermal insulation based of the principle of aheat pipe.

FIG. 5 is an axial cross-section of a cryosurgical instrument with acoaxial tubular piece joined at its distal end with the external shaft.

FIG. 6 demonstrates an axial cross-section of a cryosurgical instrumentwith application of the coaxial intermediate lumen instead of thecoaxial tubular piece.

FIG. 7 is an axial cross-section of a cryocatheter for preventingrestenosis of blood vessels.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows the general view of the cryosurgical instrument and itsaccessory device. The drawing demonstrates following units: acryosurgical instrument 100 with cryotip 116 and an elongated tubularsub-unit 105. The accessory system comprises: a thermo-insulated tank(or a Dewar flask) 101 with cryogenic liquid, this thermo-insulated tank101 is provided with a relief valve 103, which gives possibility topreset a desired pressure in the thermo-insulated tank, a shut-off valve102 that serves for filling the thermo-insulated tank 101 with thecryogenic liquid, and manometer 104.

A multi-way valve 107 is communicated with: a feeding pipe 106 situatedin the thermo-insulated tank 101; a vacuum pump or atmosphere (via duct121); the cryosurgical instrument 100 by a main duct 112: bottle 108with pressurized gas. Sensor 111 controls preset changeover frequency ofthe multi-way valve 107. In addition, there are pressure and temperaturegauges 114 and 120 installed on the main duct 112. Data provided fromthese sensor and gauges are processed in a control unit 115. In the caseof significant deviations of the measured parameters from the presetvalues, the control unit 115 cuts off the shut-off valves 109, 110 and113.

In addition, there is bottle 117 filled with a gas with low thermalconductivity, for example, R14. This bottle is communicated via duct 119with the external chamber of the cryosurgical instrument 100 (the gapsbetween the external shaft of the cryosurgical instrument 100, and itscoaxial tubular piece, and the external shaft and the proximal sectionof the central feeding-venting lumen). A three-way valve 118 installedon duct 119 serves for filling the external chamber by charging andpurging technique, this filling should be performed previously toactuating the cryosurgical instrument 100 and performance of cryogenictreatment.

FIG. 2 shows a cryosurgical instrument 200 and its accessory system inthe case, when this cryosurgical instrument comprises a coaxialintermediate lumen instead of the coaxial tubular piece and there isoscillating flow in the channel between the central feeding-ventinglumen and the coaxial intermediate lumen of the cryosurgical instrument.The cryosurgical instrument 200 consists of two major sub-units: 1)cryotip 217; 2) elongated tubular sub-unit 218.

The accessory system comprises a thermo-insulated tank (or a Dewarflask) 201 containing cryogenic liquid, this thermo-insulated tank 201is provided with a relief valve 203 which gives possibility to preset adesired pressure in the thermo-insulated tank 201, valve 202 whichserves for filling the thermo-insulated tank 201 with the cryogenicliquid, and manometer 204.

A multi-way valve 208 of the accessory system is communicated withfollowing details: a feeding pipe 205 situated in the thermo-insulatedtank 201; a vacuum pump or atmosphere; the cryosurgical instrument 200(by a main duct 215); bottle 210 with pressurized gas. In addition,there is a three-way valve 211, which is joined mechanically by coupling212 with the multi-way valve 208. The three-way valve is communicatedwith the channel between the coaxial intermediate lumen and the centralfeeding-venting lumen of the cryosurgical instrument 200 by duct 222,the atmosphere (or vacuum pump) and bottle 210 with pressurized gas. Ashut-off valve 213 is installed on the duct, which communicates bottle210 with the three-way valve 211. Coupling 212 is designed in such away, that when the multi-way valve 208 communicates the main duct 215with the atmosphere (or vacuum pump), then the three-way valve 211communicates duct 222 with bottle 210 and vice versa, the three-wayvalve 211 communicates ducts 222 with the atmosphere (or vacuum pump)when the multi-way valve 208 communicates the main duct 215 with bottle210.

Sensor 209 controls a preset changeover frequency of the multi-way valve208. Data provided from this sensor are processed in a control unit 223.In the case of significant deviations of the measured parameters fromthe preset values, the control unit 223 cuts off a shut-off valve 207,which is installed on duct 206 communicating the feeding pipe 205 withthe multi-way valve 208, a shut-off valve 214 installed on a ductcommunicating bottle 210 with the multi-way valve 208, a shut-off valve216 installed on the main duct 215 and the shut-off valve 213 installedon a duct communicating bottle 210 with the three-way valve 211.

In addition, there is bottle 219 filled with a gas with low thermalconductivity, for example, R14. This bottle is communicated via duct 220with the external chamber of the cryosurgical instrument 200 (the gapbetween the external shaft of the cryosurgical instrument 200 and itscoaxial intermediate lumen). A three-way valve 221 installed on duct 220serves for filling the external chamber of the cryosurgical instrument200 with the gas with low thermal conductivity by charging and purgingtechnique. This filling should be performed previously to actuating thecryosurgical instrument 200 and performance of cryogenic treatment.

FIG. 3 shows a general view of a cryosurgical instrument of the presentinvention and a block diagram of its accessory system, when twodifferent liquids are used for preliminary ice-mapping and followingcryogenic treatment.

In addition, this drawing demonstrates a general view of a cryosurgicalinstrument and a block diagram of its accessory system in the case ofapplication of two different liquids for freezing and fast thawing atarget tissue.

The drawing shows following units: a cryosurgical instrument 300 withcryotip 332 and an elongated tubular sub-unit 333. The accessory systemcomprises: a first tank 301 filled with first liquid with cryogenicboiling temperature (for example, liquid nitrogen), this first tank 301is provided with: a relief valve 302, which gives possibility to presetthe desired pressure in the first tank 301; valve 304 which serves forfilling the first tank 301 with the first liquid and manometer 303.

A multi-way valve 310 is communicated by duct 306 with followingdetails: a feeding pipe 305 situated in the first tank 301; a vacuumpump or the atmosphere; the cryosurgical instrument 300 by a main duct322, this main duct splits off into two ducts 313 and 337; bottle 308with a first pressurized gas. A shut-off valve 307 is installed on duct306, a shut-off valve 338 is installed on duct 313 and a shut-off valve309 is installed on a duct that communicates bottle 308 with themulti-way valve 310. Sensor 312 controls preset changeover frequency ofthe multi-way valve 310. Data provided from this sensor are processed ina control unit 331. In the case of significant deviation of the measuredparameter from a preset value, the control unit 331 cuts off theshut-off valves 307,338 and 329.

In addition, the accessory system comprises a second tank 314 filledwith second liquid with relatively high boiling temperature (forexample, R12B 1), this second tank 314 is provided with: a relief valve315 which gives possibility to preset the desired pressure in the secondtank 314; valve 317 which serves for filling the second tank 314 withthe second liquid; manometer 316.

A multi-way valve 321 is communicated with following details: by duct319 with a feeding pipe 318 situated in the second tank 3141; a vacuumpump or the atmosphere; the cryosurgical instrument 300 by a main duct322 and duct 337; bottle 323 with a second pressurized gas. A shut-offvalve 320 is installed on duct 321, a shut-off valve 325 is installed onduct 324 communicating bottle 323 with the multi-way valve 321 and ashut-off valve 326 is installed on duct 337. Sensor 330 controls presetchangeover frequency of the multi-way valve 321. Data provided from thissensor are processed in a control unit 331. In the case of significantdeviation of the measured parameter from a preset value, the controlunit 331 cuts off the shut-off valves 320, 325 and 326.

Bottle 328 with a third pressurized gas is communicated by duct 327 withducts 337 and 322. A three-way valve 328 is installed on duct 327, thisthree-way valve is communicating with the atmosphere as well and thecontrol unit 331 controls it. The three-way valve 329 serves for blowingthe ducts and the cryosurgical instrument 300 itself after a stage ofice-mapping (or thawing) in order to remove the second liquid and itsvapors. Charging and purging technique performs the blowing process.

In addition, there is bottle 334 filled with a gas with low thermalconductivity, for example, R14. This bottle is communicated by duct 335with the external chamber of the cryosurgical instrument 300 (the gapbetween the external shaft of the cryosurgical instrument 300, and itscoaxial tubular piece and the proximal section of the centralfeeding-venting lumen). A three-way valve 336 installed on duct 335 andcommunicated as well with the atmosphere serves for filling the externalchamber of the cryosurgical instrument 300 by charging and purgingtechnique, this filling should be performed previously to actuating thecryosurgical instrument 300 and performance of cryogenic treatment.

FIG. 4 shows an axial cross-section of a cryosurgical instrument 400with application of active thermal insulation based of the principle ofa heat pipe.

The cryosurgical instrument is constructed from two major sub-units: adistal cryotip 402, which serves for immediate contact with a targettissue; freezing action of this cryotip is obtained by evaporation ofcryogenic liquid on its internal porous coating 403 formed from porousmetal with open porosity; an elongated tubular sub-unit serving fordelivery of portions of the cryogenic liquid on the internal porouscoating 403 with following removal of vapors generated in the process ofboiling this cryogenic liquid in the internal porous coating 403.

The elongated tubular sub-unit in turn comprises following details: anexternal shaft 404; a central feeding-venting lumen 401, which servesfor immediate supply of portions of the cryogenic liquid to the internalporous coating 403 of the distal cryotip 402 and, at the same time, forremoval of the vapors, generated in the process of boiling the cryogenicliquid in this internal coating 403, into the atmosphere or into avacuum pump.

In addition, there is a coaxial tubular piece 405 positioned in the gapbetween the distal sections of the central feeding-venting lumen and theexternal shaft 404; the distal end of this coaxial tubular piece 405 issealed with cryotip 402 and the proximal end-with the centralfeeding-venting lumen 401.

The outer surfaces of the coaxial tubular piece 405 and a section of thecentral feeding-venting lumen 401 mating this coaxial tubular piece arecovered with a porous coating 406 with open porosity, this porouscoating is functioning as a wick when the gap between the external shaft404, the coaxial tubular piece 405 and the mating section of the centralfeeding-venting lumen 401 is filled with vapors of such a gas that itscondensation temperature is higher than the boiling temperature of theapplied cryogenic liquid.

The proximal end of the feeding-venting central lumen is provided withan inlet-outlet connection 407, and the proximal section of the externalshaft 404 is provided with an inlet-outlet connection 408.

FIG. 5 is an axial cross-section of a cryosurgical instrument with acoaxial tubular piece joined at its distal end with the external shaft.

Cryocatheter 500 (or cryoprobe) is constructed from two major subunits:a distal cryotip 502, which serves for immediate contact with a targettissue, freezing action of this cryotip is obtained by evaporation of acryogenic liquid in its internal porous coating 503 formed from porousmetal with open porosity; an elongated tubular sub-unit serving fordelivery of portions of the cryogenic liquid on the internal porouscoating 503 with following removal of vapors generated in the process ofboiling this cryogenic liquid in the internal porous coating 503.

The elongated tubular sub-unit in turn comprises following details: anexternal shaft 504 and a central feeding-venting lumen 501, which servesfor immediate supply of portions of the cryogenic liquid to the internalporous coating 503 of the distal cryotip 502 and, at the same time, forremoval of the vapors generated in the process of boiling the cryogenicliquid on this internal porous coating 503 into the atmosphere or into avacuum pump.

In addition, there is a coaxial tubular piece 505 positioned in the gapbetween the distal sections of the central feeding-venting lumen 501 andthe external shaft 504; the distal end of this coaxial tubular piece 505is sealed with the external shaft 504 and its proximal end—with thecentral feeding-venting lumen 501. The proximal end of thefeeding-venting central lumen 501 is provided with an inlet-outletconnection 506, and the proximal section of the external shaft 504 isprovided with an inlet-outlet connection 507.

FIG. 6 demonstrates an axial cross-section of the cryosurgicalinstrument with application of a coaxial intermediate lumen instead ofthe coaxial tubular piece.

A cryosurgical instrument 600 is constructed from two major sub-units: adistal cryotip 602, which serves for immediate contact with a targettissue; freezing action of this cryotip is obtained by evaporation of acryogenic liquid on its internal porous coating 603 formed from porousmetal with open porosity; an elongated tubular sub-unit serving fordelivery of portions of the cryogenic liquid on the porous coating withfollowing removal of vapors generated in the process of boiling thiscryogenic liquid in the internal porous coating 603.

The elongated tubular sub-unit in turn comprises following details: anexternal shaft 604 and a central feeding-venting lumen 601, which servesfor immediate supply of portions of the cryogenic liquid to the internalporous coating 603 of the distal cryotip 602 and, at the same time, forremoval of the vapors, generated in the process of boiling the cryogenicliquid in this internal coating 603, into the atmosphere or into avacuum pump.

In addition, there is a coaxial intermediate lumen 605 positioned in thegap between the central feeding-venting lumen 601 and the external shaft604; the distal end of this coaxial intermediate lumen 605 is sealedwith the external shaft 604 and the proximal end—with the centralfeeding-venting lumen 601. In addition, the proximal end of the externalshaft 604 is sealed with the proximal section of the coaxialintermediate lumen 605. The proximal end of the feeding-venting centrallumen 601 is provided with an inlet-outlet connection 607, the proximalsection of the external shaft 604 is provided with an inlet-outletconnection 609 and proximal section of the coaxial intermediate lumen605 is provided with an inlet-outlet connection 608. Significant part ofthe outer surface of the coaxial intermediate lumen 605 is covered witha porous coating 606 leading off with the proximal end of theintermediate lumen, this porous coating serves as a wick in the case ofapplication of the principle of a heat pipe for heating the distalsection of the external shaft.

FIG. 7 demonstrates an axial cross-section of the catheter forpreventing restenosis of blood vessels.

Cryocatheter 700 is constructed from two major sub-units: a distalcryotip, which serves for immediate contact with a target tissue;freezing action of this cryotip is obtained by evaporation of acryogenic liquid in an internal porous coating 704 formed from porouselastic polymer with open porosity on the internal surface of anexternal tubular piece 703, which is made from elastic polymer as well.

The distal end of external tubular piece 703 is sealed by plug 702manufactured from polymer material with low thermal conductivity.

1. A method for cryogenic treatment of a patient, comprising: contactinga portion of the patient with a cryosurgical instrument, said instrumenthaving a tip; delivering a cryogen to said tip; and repeating saiddelivering said cryogen to said tip at least once while said tip is incontact with at least a portion of the patient, wherein controlling saiddelivering of said cryogen to said tip also controls temperature at saidtip, such that the delivering and the repeating said delivering produceat least one freezing stage and at least one higher temperature freezingstage.
 2. The method of claim 1, wherein said portion of the patientcomprises a blood vessel.
 3. The method of claim 2, wherein thecryogenic treatment is for prevention of restenosis.
 4. The method ofclaim 1, wherein said instrument comprises at least one valve forcontrolling said delivering said cryogen and wherein said repeating saidcryogen to said tip at least once comprises: closing said valve to stopdelivering said cryogen; and opening said valve to again deliver saidcryogen.
 5. The method of claim 4, wherein said valve comprises amulti-way valve, and wherein said opening said valve to again deliversaid cryogen comprises: opening said multi-way valve to a first state toexpel said cryogen to the atmosphere; closing said first state; andopening said multi-way valve to a second state to deliver said cryogen.6. The method of claim 4, wherein said valve comprises a plurality ofvalves, and wherein said opening said valve to again deliver saidcryogen comprises: opening a first valve of said plurality of valves toexpel said cryogen to the atmosphere; closing said first valve; andopening a second valve of said plurality of valves to deliver saidcryogen.
 7. The method of claim 6, wherein said instrument furthercomprises a control unit and wherein said control unit controls saidopening and said closing of said valves to control temperature at saidtip.
 8. The method of claim 7, further comprising determining saidtemperature at said tip by said control unit; and controlling saidopening and said closing of said valves by said control unit accordingto said temperature.
 9. The method of claim 1, wherein said deliveringsaid cryogen to said tip comprises: pressurizing said cryogen for rapiddelivery to said tip.
 10. The method of claim 9, wherein saidpressurizing comprises applying gas to said cryogen.
 11. The method ofclaim 1, wherein said cryogen comprises a plurality of cryogens havingdifferent properties.
 12. The method of claim 1, wherein said cryogencomprises at least one cryogenic liquid.
 13. The method of claim 12,wherein said cryogen comprises a plurality of cryogenic liquids.
 14. Themethod of claim 1, further comprising ablating tissue of said portion ofthe patient through said at least one freezing stage and said at leastone higher temperature freezing stage.
 15. The method of claim 1,wherein said cryogen is delivered in a plurality of portions and whereinsaid temperature is controlled at said tip according to a frequency ofrepeating said delivering of said portions of said cryogen to said tip.